Anode cooling system



Patented Oct. 11, 1949 2,484,542 ANODE COOLING SYSTEM Wilfrid L. Atwood, Newton Lower Falls, Mass.,

assignor to The Girdler Corporation,

Louisville,

Ky., a corporation of Delaware Application May 15, 1946, Serial No. 669,997

8 Claims.

This invention relates to anode cooling systems of the type particularly adapted for the cooling of the anodes of oscillators or electrical generators, and has for an object the provision of a cooling system which combines the advantages of air cooling and liquid cooling systems without their disadvantages.

In the design of radio tube oscillators or highfrequency generators, the power dissipated in the tubes presents a major problem. As the power output increases, the power dissipate-d in the'tube in the form of heat likewise increases. Where small tubes, of low power rating, are utilized, the anodes may be radiation-cooled. As the size increases, it has been the practice to attach cooling fins and to arrange a fan to circulate air to take care of the dissipation of power at the anode. While air cooling has been utilized, it is not particularly eflicient and tubes must be operated with lower rated loads than the same tubes in systems which provide water cooling. For example, a tube of the type known as the 892 has a rated dissipation of ten kilowatts if the anode be water cooled but for the same tube with fins attached to the anode and an air blower to circulate air through the fins, the ratin of the tube is only four kilowatts.

When it is realized that the air cooling requires not only the fan, the motor for driving it, but also the air ducts, it will be understood water or liquid cooling would seem highly desirable. The difliculty with water cooling the tubes as usually practiced, however, is the need to provide a source of water, which preferably should be distilled or otherwise free of impurities. The usual water cooling system is heavy and cannot be used where the high-frequency generator is to be. portable. Circulation of tap water ordinarily is not feasible, due to the deposition of scale and the resulting shortened tube-life.

It is an object of the present invention to provide a cooling system which is self-contained, which does not add sufiiciently to the weight and volume as to prevent portability of the high-frequency generator, and which is highly efficient.

In carrying out the invention in one form thereof, there is provided a cooling system for the anode of the tube characterized by a radiator in which there is maintained a low level of water and from which the water or liquid is circulated around the anode of the tube. Air may be purged from the vapor space by a valve similar to the common type of thermostatic valve such as used in the ordinary household heating system. Such a valve would pass air but not steam. It would,

r 20 and the broken line of course, readmit air on cooling. Thereforethe system would never be subjected to vacuum and the seals would only have to be designed for pressure. The pressure and temperature in the vapor space rise in accordance with the well established steam tables and the increased temperature of the vapor will give a greater temperature difference between the condensing vapor and the cooling air. At some temperature and pressure therate of condensation and the rate of evaporation will be equal. The vapor temperature will rise until this equalization occurs.

For a more detailed understanding and for further objects and advantages thereof, reference is to be had to the following description taken in conjunction with the accompanying drawing in which there is diagrammatically illustrated a system embodying the invention.

Referring to the drawing, the invention in one form has been shown as applied to a vacuum tube In having an anode ll disposed within a water jacket or heat exchanger I2. Suitable sealing means is provided at l3 to form a water-tight connection between the upper end of the jacket l2 and the anode H. The jacket I2 is always full of water l4 which circulates by way of a pipe connection IS, a length of rubber tubing l6, and a pipe ll to a radiator l8. The radiator l8 preferably consists of a plurality of vertical tubes and fins which, extend between an upper chamber ltd and a lower chamber [9 in which the water level is maintained above the point of entry of the pipe ll therein. For example, the water level may be maintained as indicated by the water gauge Zl. The return circuit by way of the pipe 22, a length of rubber tubing 23, and the pipe 24 to the jacket l2. To maintain a high rate of fiow of cooling liquid, a pump 25 is included in the return line forcibly to circulate water around the anode ll and in the same direction as that due tothe thermo-siphon action. The rate of flow of the cooling water is maintained high enough to insure removal of steam bubbles as fast as they may form on or around the anode ll. Since these steam bubbles will form even though the average temperature of the water leaving the jacket [2 is below the vaporizing point, it is important that they be removed at once in avoidance of hot spots. By maintaining a high velocity on the cooling water, the bubbles are swept away as rapidly as they form. Effective cooling is maintained at all times.

The radiator it, except in respects discussed below, is of conventional design and may be genior the cooling water is jacket, said system having a fluid level above said inlet and said outlet, and said radiator providing a confined vapor space above said level in which the pressure varies with the temperature to regulate the rate of condensation of fluid received from said jacket.

2. A cooling system comprising an anode of an electric tube having a water jacket sealed around the anode, a radiator sealed from atmosphere and having in the lower portion thereof an inlet and an outlet and in the upper portion thereof a closed vapor chamber, means forming a closed system between said inlet and said outlet and said fluid jacket, and means for forcibly circulating water through said system and around said anode as a continuous stream, said radiator in the combination having the characteristic that it is self-regulating as to the rate of condensation in said vapor chamber in that the pressure varies therein with the water temperature to maintain the rate of condensation adequate to maintain said water level above said inlet and said outlet.

3. A cooling system comprising an anode of an electric tube having a water jacket sealed around the anode, a sealed radiator located with its water-level above the uppermost part of said jacket, pipe connections extending from said radiator to the upper and lower portions respectively of said water jacket, said radiator being air-tight to provide a sealed water-circulating system, said radiator also having a confined vapor space above the normal level of water therein, a fan for circulating air in heat exchange relation with said vapor space for removal of heat therefrom, means included in one of said pipe connections for forcibly circulating watertherethrough and into high velocity contact with said anode, said radiator in the combination having the characteristic that the pressure within said vapor chamber is at room temperature, below atmospheric pressure.

4. The method of cooling the anode of a thermionic tube which comprises circulating liquid as a continuous stream in a closed path isolated from atmospheric pressure, at one region in said path passing the stream over the anode to effect transfer of heat therefrom and to sweep away steam bubbles that may form on the anode at a subsequent region in said path effecting evaporation from the surface of the liquid stream to cool it, collecting the vapor in a confined space to produce on the liquid enhanced pressure increasing its boiling point, cooling and recondensing the vapor, and returning the condensate to the stream further to reduce its temperature in advance of said first-named region.

5. The method of cooling the anode of an electronic tube which comprises forcibly circulating cooling liquid, in a path closed to atmosphere, as a continuous stream which in one region of its path flows over said anode to abstract heat therefrom and at a rate high enough to insure immediate removal of gas bubbles formed at the anode, at a subsequent region along said path removing heat from the stream by evaporation from the surface thereof into a confined space bounded by metallic wall structure, passing air over the exterior of said wall structure to condense said vapors and to cool the resulting condensate to lower temperature, and returning the condensate to said stream in advance of said first-named region to reduce the temperature of the stream before again flowing over said. anode.

6. A cooling system for the anode of an electronic tube provided with a cooling liquid jacket sealed about the anode, comprising a radiator disposed with its inlet and outlet above said jacket and constructed with said inlet and outlet below the level of cooling liquid therein, a flow connection from the upper portion of said jacket to said radiator inlet, a flow connection from the outlot of said radiator to the lower portion of said. jacket, and a pump in one of said connections forcibly to circulate said cooling liquid as a continuous stream upwardly through said jacket at a rate insuring immediate removal of gas bubbles formed at the anode, said radiator providing above the stream of cooling liquid therein a closed evaporating /condensing chamber in which vapors rising from the stream are condensed and returned to the stream.

'7. A cooling system containing a predetermined quantity of cooling liquid and adapted for the cooling of the anode of an electronic tube, including in combination a cooling liquid jacket sealed about the anode and flooded with said liquid, a radiator disposed with its inlet and outlet above said jacket and constructed with said inlet and outlet below the level of cooling liquid in the radiator, whereby said inlet and outlet of the radiator remain flooded with liquid at all times, a connection from said radiator inlet to the upper portion of said jacket, and a pump having its out let connected to the lower portion of said jacket and its inlet connected to the radiator outlet forcibly to circulate said cooling liquid as a con tinuous stream passing upwardly through said jacket at high velocity to sweep away gas bubbles at the anode and thence through said radiator, said radiator providing above the stream of cooling liquid therein a closed evaporating/condensing chamber in which vapors rising from the stream are condensed and returned to the stream.

8. A cooling system for the anode of an electronic tube having a cooling jacket sealed about the anode, comprising a closed path for circulation of coolant in liquid phase including a radiator having its inlet and outlet above said jacket and having connections therefrom to said jacket, a pump in one of said connections forcibly to circulate the liquid coolant in said path upwardly through said jacket and upwardly to the radiator, said radiator having a closed evaporating/condensing chamber containing liquid coolant above said inlet and outlet and in which evaporation and condensation of the coolant are continuously effected without interruption of the continuity of said liquid path.

WILFRID L. A'I'WOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,621,755 Rushmore Mar. 22, 1927 1,905,811 Culver Apr. 25, 1933 2,321,882 Wallace June 15, 1943 2,352,893 Hansell July 4, 1944 FOREIGN PATENTS Number Country Date 225,177 Great Britain July 16, 1925 226,903 Great Britain Jan. 8, 1925 

